Netflix Eureka: The Tool That Services Play “Hide and Seek” With at the Top Level

4 min readJul 19, 2024

Netflix Eureka is the equivalent of a magic wand for service discovery in a microservices architecture. That’s how Eureka ensures all those services can find each other and communicate, with solutions that might bring you as much joy as eating chocolate cake. In this article, we will discuss the important aspects of Netflix Eureka, how it works, and a sample application using it. Are you ready to enter into this mysterious world of services?

What is Netflix Eureka?

Netflix Eureka is an open-source service discovery tool developed at Netflix. Summary: “We know how to do this stuff.” In a microservices architecture, it is used for the dynamic location and management of different services. In distributed systems running on Amazon Web Services, Eureka is like a savior — saving you from rivaling services.

Here’s the playful illustration of Netflix Eureka in a microservices architecture within a simplified digital town square. The Eureka Server is depicted as a central, powerful figure, while the Eureka Clients are smaller characters communicating with the server. The colorful and engaging style conveys the joy of service discovery and dynamic configuration. (— Generated By DALL-E)

Key Features

Service Registration and Discovery: Services register with the Eureka server and can be discovered by other services. Think of it as Facebook, but without the drama.
Health Checks: Services are checked on regularly for good health and kept up-to-date. No sick services are allowed!
High Availability: High availability is provided with multiple Eureka server setups. No more “I didn’t know” excuse; everyone is prepared around here!
Dynamic Configuration: The services are dynamically configured and updated. New update? It’s child’s play with Eureka!

Architecture of Eureka

Eureka has two main superpowers:

Eureka Server: the central superhero where services register and get discovered
Eureka Client: the other superhero, letting services register with the Eureka server and discover other services. The whole of the two behave like a Batman and Robin.

Sample Application

Let’s now build a sample application which is playful and also supports Eureka Server and Eureka Client.

1. Setup Eureka Server

First let’s develop the Eureka Server. We can build a eureka server very easily using Spring Boot.

Add necessary dependencies to our pom.xmlfile:

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
    </dependency>
</dependencies>

Next, create our main class and define it as a Eureka Server:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.server.EnableEurekaServer;

@SpringBootApplication
@EnableEurekaServer
public class EurekaServerApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaServerApplication.class, args);
    }
}

Configure the application.yml file:

server:
  port: 2424

eureka:
  client:
    register-with-eureka: false
    fetch-registry: false
  server:
    enable-self-preservation: false

After these steps, we can start the Eureka Server. Now we’re ready to register our services. The Eureka Server is like a town square where services shout, “I’m here!”

2. Setting Up Eureka Client

Now, let’s create a Eureka Client that will register with the Eureka Server. We’ll again use Spring Boot for this.

Add the necessary dependencies to our pom.xml file:

<dependencies>
    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
    </dependency>
</dependencies>

Create our main class and define it as a Eureka Client:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class EurekaClientApplication {
    public static void main(String[] args) {
        SpringApplication.run(EurekaClientApplication.class, args);
    }
}

Configure the application.yml file:

server:
  port: 8080

eureka:
  client:
    serviceUrl:
      defaultZone: http://localhost:2424/eureka/

After these steps, we can start the Eureka Client and see it registered on the Eureka Server. The Eureka Client shouts “I’m here!” as it registers with the Eureka Server.

Advanced Topics

We have learned about the basics of Eureka. Let’s dive a little deeper.

High Availability

Eureka is also capable of high availability and therefore can be used across large distributed systems. Many Eureka servers can be established so that the services are always at hand. It balances the load among the services, making sure that the fastest and the most appropriate service is always operational.

eureka:
  instance:
    hostname: eureka-peer1
  client:
    serviceUrl:
      defaultZone: http://eureka-peer2:2424/eureka/

Health Checks And Restart

Eureka checks the health of services at an interval. When a service is not functioning, Eureka detects it and notifies the other services. This is to ensure that your system remains healthy and running at all times.

import org.springframework.boot.actuate.health.Health;
import org.springframework.boot.actuate.health.HealthIndicator;
import org.springframework.stereotype.Component;

@Component
public class CustomHealthIndicator implements HealthIndicator {
    @Override
    public Health health() {
        // Define your health check here
        boolean healthy = checkHealth();
        if (healthy) {
            return Health.up().build();
        } else {
            return Health.down().withDetail("Error", "Something went wrong").build();
        }
    }

    private boolean checkHealth() {
        // Define your health check logic here
        return true;
    }
}

Conclusion

Netflix Eureka is an extremely powerful, enjoyable tool for dynamically discovering and managing services in distributed systems. We have discussed the main features of Eureka and how to use them with a simple example here. Eureka ensures that service discovery is easy, reliable, and interoperable — that is the place where it makes the job more enjoyable. It is similar to how GPS would guide you to the right service!